Ruby script to copy files from one S3 bucket to another using aws-sdk

transfer.rb

require 'aws-sdk'

class Transfer
  def initialize(from_bucket, to_bucket)
    @s3 = AWS::S3.new

    @from_bucket = @s3.buckets[from_bucket]
    @to_bucket = @s3.buckets[to_bucket]

    raise "#{from_bucket} does not exist" unless @from_bucket.exists?
    raise "#{to_bucket} does not exist" unless @to_bucket.exists?
  end

  def transfer(for_real = false)
    puts "Loading keys..."
    keys = load_keys_to_transfer(@from_bucket)
    puts " - Found #{keys.size} keys to transfer"

    stats = Hash.new(0)
    count = 0

    for key in keys do
      count += 1
      print "Copying %5d/%5d - " % [count, keys.size]
      pkey = key.clone
      if key.length > 50
        pkey = "...#{key[-50,50]}"
      end
      puts pkey
      from_object = @from_bucket.objects[key]
      to_object = @to_bucket.objects[key]

      if to_object.exists?
        stats[:already_copied] += 1
      else
        begin
          from_object.copy_to(to_object, :acl => :private) if for_real
          stats[:copied] += 1
        rescue Exception => ex
          stats[:errors] += 1
          puts " --> EXCEPTION: #{ex.message} (key: #{key})"
        end
      end
    end

    puts "All done with #{keys.size} keys"
    puts "Stats: #{stats.inspect}"
  end

  private

    def load_keys_to_transfer(bucket)
      keys = []
      bucket.objects.each { |obj| keys << obj.key }
      return keys
    end

end